A photonic (or optical) network generally refers to a communications network in which information is transmitted entirely in the form of optical signals. A great deal of time and effort is spent in the commissioning of a photonic network. The commissioning of a photonic network is particularly difficult in a network installation phase, as photonic network elements are interconnected by dark fibers. A dark fiber is an optical fiber that is currently installed but not being used. Optical fibers convey information in the form of light pulses. Therefore, dark fibers imply that no light pulses are being sent.
Generally, users (e.g., craft persons) follow instructions of network planners to interconnect nodes located approximately 20-30 kms apart. For example, a fiber link connected to port ‘1’ of a node A is to be connected to port ‘a’ of a distant node B. The problem that may arise is whether users at node A and node B can be sure that they have each selected the same fiber from a bundle of fibers, or whether they have connected the fibers to the assigned ports at either end. Without a light source, establishment of correct fiber connectivity is labor intensive and time consuming.
In a Dense Wavelength Division Multiplexing (DWDM) photonic network, photonic network elements (e.g., nodes) may be interconnected by interconnecting fibers for transporting data carried by optical signals. These interconnecting fibers are dark fibers until they are lit by data carrying optical signals. The data carrying optical signals may be generated at an external peripheral or subscriber node. As such, the photonic network is transparent to the data carrying optical signals.
A dedicated channel may be embedded in each interconnecting fiber to enable nodes to exchange control and management messages. Such a designated channel may be known as an optical Supervisory Channel (OSC). Each OSC has a dedicated light source for transmitting optical signals from a source node to a destination node. In addition, each OSC has a dedicated optical detector in the source node to receive the return path optical signal from the destination node. An OSC unit may exist in each node to support electro-optics functionality and inter-nodal messaging capabilities. Thus, each interconnecting fiber may carry an OSC even though it is operating as a dark fiber for data traffic.
Interconnection of OSCs in a communication network forms an overlay network for control and management functionality. The OSCs may be Internet Protocol (IP) based where control and management functions in each node exchange information using IP messages.
For connectivity verification, a current verification method involves applying a light source at a first end of a fiber link. At a second end, a user is required to identify a specific fiber among a fiber bundle with a light signal from the light source, thereby identifying an end to end link. This link may then be connected to specific ports at either end. If there is a fiber cut in that link, the user at the second end will not be able to detect a light signal from any fiber in the fiber bundle. Thus, the user is not able to identify the correct fiber, or the user may select a wrong fiber from the fiber bundle. The process required to correct this predicament is time consuming and labor intensive.
Another current verification method involves interconnecting inter-nodal fibers and utilizing a built-in IP control plane (e.g., Open Shortest Path First (OSPF)) protocol to discover an inter-nodal fiber link topology. This process may yield a topology map for confirming the number of links interconnecting the nodes. However, the OSPF protocol does not associate the fiber links with their respective ports. Therefore, the OSPF protocol does not provide information to confirm proper fiber connectivity.
In view of the foregoing, it would be desirable to provide a technique for verifying fiber connectivity which overcomes the above-described inadequacies and shortcomings. More particularly, it would be desirable to provide a technique for verifying fiber connectivity in an efficient and cost effective manner.